There was an equal number of grey and blue marbles in a box at first. After 27 blue marbles were taken out and 31 grey marbles were added into the box, there was
13 as many blue marbles as grey marbles. Find the number of blue marbles in the box at first.
| |
Grey marbles |
Blue marbles |
| Before |
3 u - 31 |
1 u + 27 |
| Change |
+ 31 |
- 27 |
| After |
3 u |
1 u |
The number of grey and blue marbles in the box is the same at first.
3 u - 31 = 1 u + 27
3 u - 1 u = 27 + 31
2 u = 58
1 u = 58 ÷ 2 = 29
Number of blue marbles at first
= 1 u + 27
= 29 + 27
= 56
Answer(s)56
